Manufacture of colored photographic images.



UNITED STATES PATENT OFFICE.

L'EON DIDIER, OF HOUHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO FARBWERKE, VORM.

OF GERMANY.

MANUFACTURE OF COLORED PHOTOGRAPHIC IMAGES.

Specification of Letters Patent.

Patented April 21,1908.

Application filedNovember 21, 1905. Serial No. 288,456.

To all whom it may concern:

Be it known that I, LEON DIDIER, a subject of the French Republic, and residing at Hochst-on-the-Main, Germany, have in vented certain new and useful 1m rovements in the Manufacture of Colored hotographic Images, of which the following is a specification.

According to French specification No. 337054 colored hotographic images are obtained in the f0 lowing manner :-A gelatin layer sensitized with bichromate is exposed to light under a 'diapositive, parts of the layer being thus rendered hard. Excess of 15 bichromate having been washed away with water, the'gelatin la er is dyed by immersion in adyestuff so ution; excess of dyestufi is removed by rinsing and a moist paper coated with gelatin is brought into close contact with the dyed layer. ner the dyestuff is said to be transferred only from the unexposed parts to the gelatin paper so that a colored positive image is produced. It appears from experiments that dyestuffs generally do not behave towards hardened or unhardened gelatin in the manner requisite for the success of the said process. If, for instance, in order to obtain a blue color, methylene blue, patent blue or crystal violet is used, for a red color, ma-

genta, safranin, or rhodamin', and for a yellow color, picric acid, tartrazin or auramin, either the exposed and unex osed parts of the gelatin layer are d ed ali re, yie ding their color uniformly to t e gelatin paper, so that no image is obtained, or the d estuif is not sufliciently retained by the ge atin and ma for the greater part be readily remove by washing with water, thus producing a feeble hazy image. Some dyestuffs have the peculiar property of producing a reversed image. Similar results have been obtained with most of the other colors, even with those of different shades. Here, too, no image or only an indistinct one is obtained. Again with some d estuffs at first an a parently good image is 0 tained but this so sequently proves useless, as it becomes indistinct owing to the dyestuff not having been sufficiently fixed by the gelatin. i

According to the present invention excellent results may be obtained if certain dyestufis are used. For instance, the mikadodyestuffs obtained from para-nitro-toluene- In this man- 'sulfonic acid, the soluble azo-dyestuffs derived from dehydro-thiotoluidin, primulin or their homologues and substitution products, natural carmin, the sulfonic-acids of indulin and nigrosin, naphthazin blue and some of the diamin colors, like diamin pure blue, di'anil blue, dianil yellow, dianil garnet and others. Of the anthraquinone dye-stuffs may be used the .arylidoanthraquinone sulfonic acids and their derivatives. 1

For example, to produce a blue image, a gelatin layer sensitized by immersion in a 4 per cent. solution of bichromate may be exposed to light under a diapositive and excess of bichromate removed by washing with water. The la er may then be immersed in an aqueous so utiom of fast blue (indulinsulfonic acid) of say 4 per cent. stren th, rinsed with water after 15 minutes and t ien brought into intimate contact with a moist gelatin paper. After about 10'minutes the paper may be removed from the layer, when 1t will be found toexhibit the image in blue. The original layer, without bein re-dyed,

image or may be colored again y immersion in a dyebath.

This process is of special importance in the The operation may be conducted, for instance, as follow s:From the 3 negatives are made 3 diapositives under which are exposed the bichromategelatin plates as described above.) The gelatin plate which corresponds with the red screen negativemay be then dyed by immersion in a solution of about 4 percent. strength of, for instance, diamin pure blue, and the image may be transferred to the gelatin paper as hereinbefore described.

The gelatin plate which corresponds with the green negative may be dyed by immersion in a solution of about 4 per cent. strength of carmin or of the azo-dyestuff from primu insulfonic acid and 1 :4:7-alpha-naphtholdisullonic acid and afterwards washed. The previously obtained blue, still moist or remoistened image may then be placed on the about 10-15 minutes the image is removed.

The gelatin plate which corresponds with lution of about 4 per cent. strength of dialiil the blue screen negative may be dyed in a somay serve several times for re ro( ucing the manufacture of three color photographs.

red plate in such a manner that the outlines cover each other, and closely pressed; after yellow B (azo-dyestufl from primulin-sulfonic acid and phenylmethyl yrazolone), excess of the dyestuff removec by rinsing with water and the blue and red image laid on sonthatthe, outlines cover each other. After about 15 minutes the finished image is removed from the plate.

Having now described my invention, what I claim is 3 The process herein described of producing colored photogra hie images on the three color-principle, wiich consists in dyeing a gelatin-layer sensitized with bichromate, exposed under a diapositive and Washed, by immersing it in an aqueous solution of sulfonic acids of indulin, then removing the eX- cess of dyestufi and bringing the dyed layer into close contact with moistened gelatin paper, then superposing the blue image thus obtained on a gelatin-layer sensitized with bichromate, exposed under a diapositive and washed, by immersing it into an aqueous solution of natural carmin, then superposing the blue and red images thus obtained on a gelatin-layer sensitized with bichromate, eX- posed under a d-iapositive and washed, by immersing it into an aqueous solution of a primulin dye.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

LEON DIDIE R.

Witnesses: I 4

JEAN GRUND, CAR-L Gnu-n1). 

